Air conditioner

ABSTRACT

This invention provides an improved air-conditioner. Basically, it comprises: a casing mountable in an opening into a room and having openings communicating with indoor and outdoor air; a refrigeration system mounted in the casing and comprising a compressor, a condenser and an evaporator interconnected in a refrigerant flow relationship by conduit means including a discharge tube connected to the compressor outlet for delivering high pressure, hot gaseous refrigerant to the condenser; and a fan mounted in the casing for circulating outdoor air over the condenser. However, in accordance with the present invention, a multi-speed electric motor is mounted in the casing with its output shaft connected to the condenser fan. The motor has a slower first speed and a faster second speed. In particular accordance with the present invention, thermally-responsive switch means are mounted on the compressor discharge tube and have a movable switch member that will remain in a first position causing the motor to operate the condenser fan at the slower and consequently quieter first speed unless the discharging gaseous refrigerant temperature is sufficiently high to cause the switch means to sense a temperature exceeding a first predetermined temperature. Then, the switch member will move to a second position causing the motor to operate the condenser fan at the faster and consequently louder second speed, but only until the discharging gaseous refrigerant temperature becomes sufficiently low to cause the switch means to sense a second predetermined temperature that is lower than the first. Then, the switch member will return to its first position causing the motor to resume operation of the condenser fan at the slower and quieter first speed.

United States Patent 1 Slattery 111 3,717,010 51 Feb. 20, 1973 [54] AIR CONDITIONER [75] Inventor: John P. Slattery, Louisville, Ky.

[73] Assignee: General Electric Company [22] Filed: July 2, 1971 [21] Appl. No.: 159,239

Primary Examiner-William J. Wye Attorney-Walter E. Rule et al.

[5 7] ABSTRACT This invention provides an improved air-conditioner. Basically, it comprises: a casing mountable in an opening into a room and having openings communicating with indoor and outdoor air; a refrigeration system mounted in the casing and comprising a compressor, a

condenser and an evaporator interconnected in a refrigerant flow relationship by conduit means including a discharge tube connected to the compressor outlet for delivering high pressure, hot gaseous refrigerant to the condenser; and a fan mounted in the casing for circulating outdoor air over the condenser. However, in accordance with the present invention, a multispeed electric motor is mounted in the casing with its output shaft connected to the condenser fan. The motor has a slower first speed and a faster second speed. In particular accordance with the present invention, thermally-responsive switch means are mounted on the compressor discharge tube and have a movable switch member that will remain in a first position causing the motor to operate the condenser fan at the slower and consequently quieter first speed unless the discharging gaseous refrigerant temperature is sufficiently high to cause the switch means to sense a temperature exceeding a first predetermined temperature. Then, the switch member will move to a second position causing the motor to operate the condenser fan at the faster and consequently louder second speed, but only until the discharging gaseous refrigerant temperature becomes sufficiently low to cause the switch means to sense a second predetermined temperature that is lower than the first. Then, the switch member will retum to its first position causing the motor to resume operation of the condenser fan at the slower and quieter first speed.

2 Claims, 2 Drawing Figures PATENTED FEB 2 01973 Jn Rm a 5 MW M fi m ms m P. m

F'IGZ AIR CONDITIONER BACKGROUND OF THE INVENTION This invention relates to air-conditioning apparatus and, more particularly, to self-contained air-conditioner units of the type adapted to be mounted in a window or other opening in the wall of a building.

Such self-contained air-conditioner units are frequently employed to cool the air within a single residential room or confined space and are widely referred to as room air-conditioners. Conventionally, such room air-conditioner units usually include a casing mountable within an opening into a room and having openings communicating with indoor and outdoor air, a refrigeration system mounted in the casing and including a compressor, a condenser and an evaporator interconnected in a refrigerant flow relationship and an electric motor-powered fan means mounted in the casing for respectively circulating indoor air over the evaporator and outdoor air over the condenser.

Frequently, the room that is to have its air cooled by such an air-conditioner unit is a sleeping room and, hence, it is desirable that the noise generated by the unit be minimized, especially during night hours which are normally utilized for sleeping. The present invention is particularly concerned with providing such a unit with control means for automatically reducing the noise generated by at least its condenser fan and, preferably, by both its condenser and evaporator fans unless the outdoor air temperature exceeds a predetermined level.

The present invention is also concerned that such automatic control means will be responsive to conditions other than outdoor air temperature alone, such as: partial blockage of outdoor air flow across the condenser, as might be caused by overgrown shrubbery; excessive compressor motor operating temperature, as might be caused by abnormally low power supply voltage; and the like.

As described in commonly-assigned U.S. Pat. No. 3,040,544 Atchison, it has been known previously to provide a room air-conditioner with non-automatic (manually-operable) control means whereby both the evaporator and condenser fans can be operated at reduced speed according to the desires of the operator to thus achieve noise reduction at certain times, such as at night when the outdoor air temperature and the cooling load of the room are both usually at a minimum. As further illustrated by U.S. Pat, Nos. 2,952,991 St. Pierre and 3,293,876 Geisler, it has also been known previously to automatically control the speed of a condenser fan in accordance with outdoor air temperature. However, such previously known automatic controls are distinguished from the present invention in that they have been mounted on the condenser-compressor sections of so-called split system central air-conditioning units that are located wholly outside of the building, rather than within a casing that is installed in an opening through the building wall, as presently described. These prior-art air-conditioners are further distinguished from the present invention in that their prior-art controls have their temperature or pressure sensors mounted at the condenser inlet or discharge, whereas the thermally-responsive control means of the present invention are mounted at the compressor discharge.

SUMMARY OF THE INVENTION Basically, the improved air-conditioner of the present invention comprises: casing means mountable 5 in an opening into a room and having openings communicating with indoor and outdoor air; a refrigeration system mounted in the casing and comprising a compressor, a condenser and an evaporator interconnected in a refrigerant flow relationship by conduit means including a discharge tube connected to the compressor outlet for delivering high pressure, hot gaseous refrigerant to the condenser; and a fan mounted in the casing for circulating outdoor air over the condenser. However, in accordance with the present invention, a multi-speed electric motor is mounted in the casing with its output shaft connected to the condenser fan. The motor has at least a first speed and a second speed, with the first speed being slower than the second speed.

In particular accordance with the present invention, thermally-responsive switch means are mounted on the compressor discharge tube and have a movable switch member that will remain in a first position causing the motor to operate the condenser fan at the slower and consequently quieter first speed unless the discharging gaseous refrigerant temperature is sufficiently high to cause the switch means to sense a temperature exceeding a first predetermined temperature. Then, the switch member will move to a second position causing the motor to operate the condenser fan at the faster and consequently louder second speed, but only until the discharging gaseous refrigerant temperature becomes sufficiently low to cause the switch means to sense a second predetermined temperature that is lower than the first, whereupon the switch member will return to its first position causing the motor to resume operation of the condenser fanrat the slower and quieter first speed.

Preferably, but not necessarily, the air-conditioner also has an evaporator fan connected to the output shaft of the multi-speed motor.

Under normal operating conditions, the temperature of the gaseous refrigerant being discharged from the compressor and the outdoor air temperature will be directly proportional to one another, with the discharging gaseous refrigerant temperature being about 30 to 40 F higher than the outdoor air temperature. Hence, with the improved structure provided by the present invention, the noise generated by the fan means of a room air-conditioner in the room cooled by it can usually be automatically reduced during the night hours when sleeping usually occurs and the outdoor air temperature is at its cooler levels.

However, by locating its control means on the compressor discharge tube, the present invention also provides that such control means will be responsive to conditions other than outdoor air temperature alone, such as the aforenoted blockage of outdoor air flow across the condenser, excessive compressor motor operating temperature, etc. which mightotherwise not be detected if the switch means were otherwise mounted or were mounted to be sensitive to outdoor air temperature alone.

BRIEF DESCRIPTION OF THE DRAWING The present invention is illustrated in the accompanying drawing, wherein:

FIG. 1 is a partly-sectioned top plan view of a presently preferred form of an improved air-conditioner that is provided in accordance with the present invention; and

FIG. 2 is a schematic diagram of a presently preferred form of electric control circuit that can be employed with the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawing and particularly to FIG. 1 thereof, there is illustrated a presently preferred form of an improved self-contained air-conditioning unit or room air-conditioner 10 that is provided in accordance with the present invention. The air-conditioner 10 comprises generally hollow box-like casing l 1 that can be easily mounted within an opening into a room, such as can be provided by a hole in a building outer wall, a window, or the like.

The casing 11 is divided by a barrier 12 into two separate compartments, including a condenser or outdoor compartment 13 and an evaporator or indoor compartment 14. A condenser heat exchanger 15 is mounted in the outdoor compartment 13 and an evaporator heat exchanger 16 is mounted in the indoor compartment 14. The condenser 15 and the evaporator 16 are connected by conduit means in a refrigerant flow relationship with an electrically-powered, hermetic compressor 17, which is also located in the condenser compartment 13. More specifically, a suction tube 18 delivers low pressure suction gas to the inlet of the compressor 17 and a discharge tube 19 is connected to the outlet of the compressor 17 for delivering high pressure, high temperature discharge gas to the condenser 15. Suitable expansion means, such as a capillary tube 20, are connected between the condenser 15 and the evaporator 16 for creating a pressure drop between the condenser 15 and evaporator 16 to promote vaporization of the liquid refrigerant flowing between the two heat exchangers l and 16.

It is intended that the casing 11 be mounted within the building wall opening with the barrier 12 arranged generally vertically and in such a manner that the condenser compartment 13 is in fluid communication with outdoor air and the evaporator compartment is in fluid communication with indoor or room air.

In order to circulate indoor air through evaporator compartment 14 for cooling, an evaporator fan 21 is mounted in the evaporator compartment 14. This evaporator fan 21 is driven by an output shaft 22 of an electric motor 23 that is connected to the barrier 12 by fastener means such as motor bolts 24 and nuts 25.

Room air is drawn into the evaporator compartment 14 via louvered casing room air inlet openings 26 and circulated past the evaporator 16 by the evaporator fan 21 and is returned to the room via louverd casing room air outlet openings 27. V

In order to circulate a stream of outdoor air past the condenser 15 a condenser fan 28 is mounted within the casing condenser compartment 13. Outdoor air is drawn into the condenser compartment 13 through louvered casing outdoor air inlet openings 29 and circulated past the condenser 15 by the condenser fan 28 and is then discharged to the outdoors via louvered casing outdoor air outlet openings 30.

As illustrated in FIGS. 1 and 2, both the evaporator fan 21 and the condenser fan 28 are powered by the same drive means, namely the electric motor 23 through its output shaft 22 that is also connected to the condenser fan 28. It should, of course, be understood that separate motors could also be used to drive each of these two fans 21 and 28. However, in accordance with the illustrated form of the present invention, a multispeed (two-speed) motor is employed for the single motor 23 that is used to drive both the evaporator and condenser fans 21 and 28. The motor 23 has at least a first speed and a second speed, with the first speed being slower than the second speed.

Preferably the two speeds of the motor 23 and the size of the condenser fan 28 are made such that operation of the motor 23 at its first or slower speed will under normal conditions provide adequate cooling for the condenser 15 unless the outdoor air temperature exceeds about F and the extra cooling required by the condenser 15 when the outdoor air temperature exceeds 95 F will be normally provided by operation of the motor 23 at its second or faster speed.

As shown in FIG. 2, the compressor 17 and fan motor 23 are connected in an electrical parallel with one another through a manually-operable fan speed control switch 31, which has a base 31a, apair of mechanically interlinked, pivotally mounted, movable switch members 31b and 310, and four fixed contacts 3ld-g. The interlinked switch members 31b and 31c can be manually moved simultaneously by means, such as a knob 31k, between a first position in which their free ends respectively engage the first 31d and third 31f fixed contacts and a second position in which their free ends respectively engage the second 31c and fourth 31g fixed contacts. The compressor 17, fan motor 23 and switch 31 are, in turn, connected in electrical series across a pair of electric power source lines L and L, with a room temperature control switch 32, which has a base 32a, a single pivotally mounted, bimetallic movable switch member 32b and a single fixed contact 32c.

As more specifically illustrated in FIG. 2, the switch member 32b has its pivoted end electrically connected bya conductor 33 to one of the power supply lines L Its opposite or freeend is movable into and out of engagement with the fixed contact 32c that is electrically connected by a conductor 34 to the pivoted end of one of the movable switch members 31b of the switch 31. The first fixed contact 31d is connected in electrical series with the compressor 17 to the other power line L by conductors 35 and 36. The first fixed contact 31d is also electrically connected to the pivoted end of the other movable switch member 31c of the switch 31 by a conductor 37, which is, in turn, electrically connected tothe second fixed contact 31c by another conductor 38. i

In particular accordance with the present invention, the fan motor 23 is electrically connected between the third and fourth fixed contacts 31f and 31g of the switch 31 and the other power line L, with thermallyresponsive switch means comprising a switch 39 that is mounted on the exterior of the discharge tube 19 in good thermal contact therewith closely adjacent to the outlet of the compressor 17 to sense the temperature of the discharging gaseous refrigerant.

The thermally-responsive switch 39 includes a base 39a, a single"pivota lly" mounted,=bimetallicmovable switch member 39b and a pair'of fixed 'contactmembers 39c and 39d. One of the fixed contacts'39c-is'electrically connected by a conductor 40to the first or low 5 speed tap 41 of the motor 23 and'the other 39d is electrically connected by a conductor 42 to the second or high speed tap 43 of the motor 23 that is,iin turn, elec trically connected by aconductor 44 to the power line L The second fixed contact 39d is also electrically connected by a conductor 45 to the fourth fixed contact 31g of the manual fan;controlswitch'31, The switch member 39b has its pivotedend electrically ,connected by a conductor 46 to thethird fixed contact 31f ofthe switch 31.- u .7

It is intended that thefree endof theebimetallic switch member 39bshall remain in a-first'position engaging the first fixed contact39c of the switch 39 and electrically connectingfthe 't'hird'fixed contact" 31f of the manual fan"control"switch31to the low speed tap 41 of the motor'23 unless the"discharging'gaseous refrigerant temperaturesensed by the" switch "39 exceeds a first predetermined temperature? Then, the switch member 395 will rn'ovfeto a s'eciori dposition engaging the second fixed contact 39d of the switch 39 and electrically,connecting the third fixedlicoritact 31f of the switch 31 to the high peed tap user the motor 23 and will remain in this 'secondpos itionjbut' qnlyj until the thermally-responsive switch 39 senses a second predetermined temperature that is lower than the first predetermined temperature, whereupon the '1 switch member39b will return toits first position,

In operation, the manual -,fan switch 31is preferably moved to its first position, :as shown in solid lines in FIG; 2, by rotating its control Eknob, 3,lk,;to,its Lo position. This will simultaneously respectively; engage the movable switch members 31b and'31c withthe first 31d andthird 31ffixed contacts o'fi the switch3l wT hen, engagement of the free end of the movable member 32b of the room air temperature control switch32 with its fixed contact 32c'will energiz'e'a first'circuit'causing operation of the compressor l7 and will simultaneously energize a second circuit causing the motor 23 to operate both theevaporator'and condeiiser fans' 2l and 28 at its slower an'diconse quently quieter first s'peed unless the discharging gaseous refrigerant "temperature sensed byv the therr'nallyfresponsiveiswitch exceeds the first predetermined emperature; The 'first'circuit includes the first power line Lg eenquerer, 33,"switch member 32b, fixed contact me, 'eenduieter 34," switch member3lb,fixed coirtact rnember iild, coriductor'3l5, compressor 17, conductor 3,-and second power line L The second circuit includes the first conductor 33, switch member 32b, fixed contact 32c,

conductor 34, switch member 31b, conductor 37, switch member 310, fixed contact 31f, conductor 46, switch member 39b, fixed contact 390, conductor 40, a low speed motor tap 41, motor 23, conductor 44, and second power line L Then, should the discharging gaseous refrigerant temperature sensed by the switch 39 exceed the first predetermined temperature, the switch member 39b will move to its second position de-energizing the second circuit and energizing a third circuit causing the motor 23 to operate both the fans 21 and 28 at its T50. 'on the discharge tube 19, the present invention provides -the' improved air conditioner- '10 r with automatic "me'an's'fo'r' controlling the speed of its fair means drive higher andeconsequently louder speed. This third circuit includes the first :powerzline L conduct or. 33, switch member 32b,'fixed contact 32c, conductor 34, switch member 31b, fixed contact 31d, conductor 37 switch member 31c, fixed contact,3lf, conductor 46, switch member 3%; fixed-contact 39d, conductor 42, high speed motor tap 43, motor 23, conductor 44, and second power line 'L The switch member 39b will remain in this second position but only until the switch 39 senses a second "predetermined temperature that is lower than the first predetermined temperature, whereupon theswitchmember 39b will return to its first position dee'nergizing the third circuit and re-energizingthesecond circuit, whereupon the motor 23 will resumeoperation 'of both'of thefans 21 and 28 at its slowerand consequently quieter speed. I

"Preferably the discharge tube-mounted thermallyresp onsive switch 39 comprises awell-knowminexpensive of-therrnostat wherein the second predetermined temperature that is required" to return the bimetallic' m ovableswitch membe'r 39b f'rom its second orvhigh'spe ed position to its 'firstor' slow speed position is about 20 F lower' tha n' the first predetermined temperature'which was first" required to cause the switch member 3912 to initially'move from its first or low speed position to its'second o'r hi gh speed position.

' Goodjresults have b'eien obtained byusing a thermostat for the switch 39 wherein the first predetermined temperature is about"l'45 F and the second predeterminedi't'emperatu're about 125 F when using the aforedescribed condenser 'fan 28} that is sized to normally provide adequate cooling for the condenser 15 at the first or slower speed operation by the motor 23 unless the. outdoor air temperature exceeds F,

whereuponoperation of" the motor 23 at the second or higher speed isthen required. With such an arrange ment,it-ha s. been found that under normal conditions the switch 39 will causethe motor 23 to resume operation';of' the efans 21-and 28 at its slower and quieter spe rwh n heput q ra r emp atu i reduced t tions, operation of the condensenfan 28'by the drive motor 23 at its second or fastergspeed reduces the refrigerantitemperatureabout 40F, whereas operation of thefqcondenser fan: 28 :by themotor -23 at its first or slower sp'eed reduces the-refrigerant temperature by only about 30F.

w r v i By locating its'thermally responsive switch means 39 motor 23 that'are-also responsive to conditions other than outdoor-airtemperature 'aloneeThe temperature of the discharging gas that is sensed by the discharge tube-mounted thermallyresponsive switch 39 could, of course, rise above the first predetermined temperature of about 145 F and remain above the second predetermined temperature of F at outdoor temperatures respectively lower than 95 F and higher than 85 F if abnormal operating conditions arose, such as the aforenoted blockage of outdoor air flow across the condenser 15, or excessive operating temperature of the motor for the compressor 17, or the like. In such an abnormal circumstance it would, of course, be desirable that the fan means drive motor 23 be operated at its second or higher speed even though the outdoor air temperature might be at levels which would cause first or lower speed operation of the fan means motor 23 under normal operating conditions, and this is provided for by the present invention.

Should the operator wish to cause the fan motor 23 to run at its second or faster speed, regardless of the temperature sensed by the discharge tube-mounted thermally-responsive switch 39, he may achieve this option by moving the manually-operable fan switch to its second position by rotating its control knob 31k to its Hi position (FIG. 2). This will simultaneously respectively engage the movable switch members 31b and 31c with the second 31e and fourth 31g fixed contacts. In this optional condition, engagement of the free end of the movable switch member 32b of the room temperature control switch 32 with the fixed contact 32c will energize a fourth circuit causing the compressor 17 to operate and will simultaneously energize a fifth circuit causing the motor 23 to operate both the fans 21 and 28 only at its faster speed. The fourth circuit includes the first power line L,, conductor 33, switch member 32b, fixed contact 32c, conductor 34, switch member 31b, fixed contact 31c, conductors 38 & 37, fixed contact 31d, conductor 35, compressor 17, conductor 36, and second power line L, The fifth circuit includes the first power Line L conductor 33, switch member 32b, fixed contact 320, conductor 34, switch member 31b, fixed contact 3 1e, conductor 38, conductor 37, switch member 310, fixed contact 31g, conductor 45, fixed contact 39d, conductor 42, high speed motor tap 43, motor 23, conductor 44, and second power line L,.

It should be apparent to those skilled in the art that while there has been described what, at the present, is considered to be the preferred embodiment of this invention in accordance with the Patent Statutes, changes may be made in the disclosed apparatus without actually departing from the true spirit and scope of this invention. It is, therefore, intended that the appended claims shall cover such modifications and applications that may not depart from the true spirit and scope of the present invention.

What is claimed is:

1. An improved air-conditioner comprising:

a. casing means mountable within an opening into a room and having openings respectively communicating with indoor and outdoor air,

b. a refrigeration system mounted in said casing means and comprising a compressor, a condenser and an evaporator interconnected in a refrigerant flow relationship by conduit means including a discharge tube connected to the compressor outlet for delivering gaseous refrigerant to the condenser;

c. a condenser fan mounted in said casing for circulating outdoor air over said condenser;

d. a multi-speed electric motor mounted in said casing and having an output shaft connected to said condenser fan,

. said motor having at least a first speed and a second speed, with said first speed being slower than said second speed; and

. thermally-responsive switch means mounted on said discharge tube for sensing the temperature of the discharging gaseous refrigerant and having a movable bimetal operated switch member operable between a first position for connecting said motor across an electric power source and causing said motor to operate at said first speed and a second position for connecting said motor across an electric power source and causing said motor to operate at said second speed,

. said movable switch member being operable to remain in said first position unless the discharging gaseous refrigerant temperature sensed by said switch means exceeds a first predetermined temperature, whereupon said switch member will then be operated to move to said second position and will remain in said second position until said switch means senses a second predetermined temperature that is lower than said first predetermined temperature, whereupon said switch member will then be operated to return to said first position such that said motor will operate said condenser fan at said slower and consequently quieter first speed unless the outdoor air temperature is sufficiently high to cause said switch means to sense a temperature exceeding said first predetermined temperature and said motor will operate said condenser fan at said faster and consequently louder second speed only until the outdoor air temperature becomes sufficiently low to cause said switch means to sense said second predetermined temperature, whereupon said motor will then resume operation of said condenser fan at said slower and quieter first speed;

145 F and being exceeded'when said condenser fan is operating at said first speed and the outdoor air temperature exceeds about F, and

i. said second predetermined temperature being about F and the temperature sensed by said switch means being as low as said second predetermined temperature when said condenser fan is operating at said second speed and the outdoor air temperature is reduced to about 85 F.

2. The invention according to claim 1 including an evaporator fan for circulating room air over said evaporator, said evaporator fan being driven by said motor whereby both of said fans operate at said slower and faster speeds.

. said first predetermined temperature being about 

1. An improved air-conditioner comprising: a. casing means mountable within an opening into a room and having openings respectively communicating with indoor and outdoor air, b. a refrigeration system mounted in said casing means and comprising a compressor, a condenser and an evaporator interconnected in a refrigerant flow relationship by conduit means including a discharge tube connected to the compressor outlet for delivering gaseous refrigerant to the condenser; c. a condenser fan mounted in said casing for circulating outdoor air over said condenser; d. a multi-speed electric motor mounted in said casing and having an output shaft connected to said condenser fan, e. said motor having at least a first speed and a second speed, with said first speed being slower than said second speed; and f. thermally-responsive switch means mounted on said discharge tube for sensing the temperature of the discharging gaseous refrigerant and having a movable bimetal operated switch member operable between a first position for connecting said motor across an electric power source and causing said motor to operate at said first speed and a second position for connecting said motor across an electric power source and causing said motor to operate at said second speed, g. said movable switch member being operable to remain in said first position unless the discharging gaseous refrigerant temperature sensed by said switch means exceeds a first predetermined temperature, whereupon said switch member will then be operated to move to said second position and will remain in said second position until said switch means senses a second predetermined temperature that is lower than said first predetermined temperature, whereupon said switch member will then be operated to return to said first position such that said motor will operate said condenser fan at said slower and consequently quieter first speed unless the outdoor air temperature is sufficiently high to cause said switch means to sense a temperature exceeding said first predetermined temperature and said motor will operate said condenser fan at said faster and consequently louder second speed only until the outdoor air temperature becomes sufficiently low to cause said switch means to sense said second predetermined temperature, whereupon said motor will then resume operation of said condenser fan at said slower and quieter first speed; h. said first predetermined temperature being about 145* F and being exceeded when said condenser fan is operating at said first speed and the outdoor air temperature exceeds about 95* F, and i. said second predetermined temperature being about 125* F and the temperature sensed by said switch means being as low as said second predetermined temperature when said condenser fan is operating at said second speed and the outdoor air temperature is reduced to about 85* F.
 1. An improved air-conditioner comprising: a. casing means mountable within an opening into a room and having openings respectively communicating with indoor and outdoor air, b. a refrigeration system mounted in said casing means and comprising a compressor, a condenser and an evaporator interconnected in a refrigerant flow relationship by conduit means including a discharge tube connected to the compressor outlet for delivering gaseous refrigerant to the condenser; c. a condenser fan mounted in said casing for circulating outdoor air over said condenser; d. a multi-speed electric motor mounted in said casing and having an output shaft connected to said condenser fan, e. said motor having at least a first speed and a second speed, with said first speed being slower than said second speed; and f. thermally-responsive switch means mounted on said discharge tube for sensing the temperature of the discharging gaseous refrigerant and having a movable bimetal operated switch member operable between a first position for connecting said motor across an electric power source and causing said motor to operate at said first speed and a second position for connecting said motor across an electric power source and causing said motor to operate at said second speed, g. said movable switch member being operable to remain in said first position unless the discharging gaseous refrigerant temperature sensed by said switch means exceeds a first predetermined temperature, whereupon said switch member will then be operated to move to said second position and will remain in said second position until said switch means senses a second predetermined temperature that is lower than said first predetermined temperature, whereupon said switch member will then be operated to return to said first position such that said motor will operate said condenser fan at said slower and consequently quieter first speed unless the outdoor air temperature is sufficiently high to cause said switch means to sense a temperature exceeding said first predetermined temperature and said motor will operate said condenser fan at said faster and consequently louder second speed only until the outdoor air temperature becomes sufficiently low to cause said switch means to sense said second predetermined temperature, whereupon said motor will then resume operation of said condenser fan at said slower and quieter first speed; h. said first predetermined temperature being about 145* F and being exceeded when said condenser fan is operating at said first speed and the outdoor air temperature exceeds about 95* F, and i. said second predetermined temperature being about 125* F and the temperature sensed by said switch means being as low as said second predetermined temperature when said condenser fan is operating at said second speed and the outdoor air temperature is reduced to about 85* F. 